ABSTRACT
Objective@#A new ion exchange column technology was used to establish an efficient and sensitive method for the detection of inorganic arsenic.@*Methods@#Based on the new As Specia Fast Column, the pretreatment methods, liquid phase separation and mass spectrometry determination conditions of inorganic arsenic in rice were optimized. Finally, arsenic compounds were separated by As Specia Fast Column and detected by liquid chromatography inductively coupled plasma mass spectrometry. The external standard method was used for quantitative analysis. The detection limit, precision and accuracy of the method were determined by measuring the content of arsenic compounds in rice samples and rice standard samples. At the same time, three Guangdong rice samples were selected as the experimental samples of this study, and 1 g of each sample was weighed and measured in parallel three times. The method was compared with the method of liquid chromatography-atomic fluorescence spectrometry (LC-AFS) and liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) in the national standard.@*Results@#The inorganic arsenic in rice was extracted with 0.5% nitric acid solution at 65 ℃ for 15 h, and the pH was adjusted to alkaline. The mobile phase A (8 mmol/L HNO3, 50 mmol/L NH3·H2O) and mobile phase B (40 mmol/L HNO3, 80 mmol/L NH3·H2O) were used as the mobile phase gradient elution (93%) . Five arsenic compounds can reach baseline separation under the conditions of RF power of 1 500 W and atomization gas flow of 0.97 L/min. The detection limits ranged from 0.114 to 0.331 μg/L, and the inorganic arsenic content in rice samples ranged from 0.063 to 0.232 mg/kg. The results of determination of arsenic compounds in rice flour reference materials were all within the uncertainty range indicated by the standard. The recoveries were 86.7%~106.7%, and the precision was 1.9%-12.5%. Compared with national standards, the results of determination of arsenate in rice were relatively close (using this method, LC-AFS, LC-ICP-MS to detect the content of arsenate in rice samples 1 was 0.231, 0.226, 0.236 mg/kg, respectively). However, due to insufficient sensitivity, the national standard method is difficult to detect low levels of arsenic compounds (Arsenobetaine was not detected in rice sample 1). The method can detect the content of arsenobetaine in rice sample 1 was 0.023 mg/kg.@*Conclusion@#The established method can meet the requirements of inorganic arsenic determination in rice, and it is more rapid and accurate than the current national standard. It can better monitor and evaluate the content of i-As in rice, and provide accurate data for comprehensively grasping and evaluating the safety of rice consumption of residents.
ABSTRACT
We investigated the carrying status of the virulence genes of Salmonella from different sources in Shijiazhuang City,China,to provide the basic data for the further risk assessment of Salmonella.A total of 186 isolates of Salmonella from different sources were collected and identified serotypes in the area of Shijiazhuang from 2011 to 2016.PCR was performed for eight virulence genes (invA,sopE,agfA,spvR,hilA,stn,pefA,shdA).These Salmonella bacteria were detected in 13 kinds of serotypes.Enteritidis is a significant advantage of the group.The above 8 virulence genes were analyzed,and the virulence genes hilA,stn and invA were the most frequently carried,their respective carrying rate were 90.3％ (168/186),86.6％ (161/186) and 82.8％ (154/186) respectively.We found the virulence genes of Salmonella from different sources were different.It is necessary to take measures to strengthen the food hygiene supervision and prevention and control of the storage and sale of raw poultry stalls in the morning market in Shijiazhuang area.